The present invention relates in general to a method and device for connecting computing devices and in particular to a method of interfacing two functionally active devices without first requiring a power down cycle of either device.
Without limiting the scope of the invention, its background is described in connection with a portable computer system coupled to an expansion base unit for operably linking one or more external peripheral devices to the portable computer system.
The increased demand for portable computer systems, such as laptop and notebook computers, has resulted in a proliferation of peripheral devices and external options designed to increase the functionality and convenience of the portable computer. One such option is commonly referred to as the expansion base or xe2x80x9cdockingxe2x80x9d unit.
In essence, a portable computer system is coupled (xe2x80x9cdockedxe2x80x9d) to the docking unit via a connector which consists of pins forming signal paths from the computer to the docking unit. The docking unit, in turn, houses one or more peripheral devices which are communicably linked to the portable computer""s microprocessor and other subsystems via the connector. The devices may include peripherals such as a harddisk drive, sound card, video card and others. In this way, a portable computer user can have both the functionality of a desktop computer and the portability of a notebook system.
Many desktop and portable computer systems run internal system configuration and diagnostic programs during the power up stage. Sometimes referred to as the Power-On-Self-Tests (xe2x80x9cPOST)xe2x80x9d, these internal program routines are used to verify the functionality of the computer""s subsystems such as the microprocessor, keyboard controller, memory systems, I/O ports, attached peripheral devices and others.
Some prior arts docking systems require that both the portable computer and expansion base unit be nonactive (power OFF) during the docking process. Still other prior art systems permit the expansion base to be ON but require the portable computer system power to be OFF. In this way the portable system internal configuration setup system (such as POST) can update the system Basic Input Output System (xe2x80x9cBIOSxe2x80x9d) by determining what devices are available via the expansion base unit and making the appropriate port assignments and interrupt signal designations.
Yet another aspect of known prior art systems is the use of dedicated buffers on the expansion base connector to maintain the expansion bus in a xe2x80x9cdeadxe2x80x9d nonoperative state and thus effectively disconnect the portable computer processor from the expansion base peripheral devices during docking. With known prior art systems power is applied to the portable system only after it has been connected to the expansion base unit. Moreover, the use of dedicated buffers increases the amount of real estate on the system printed circuit board and increases overall system cost.
It is herein recognized that a need exists for a method or device to connect the portable system to the expansion base unit that did not require the portable system power to be turned OFF and the use of dedicated buffers on the expansion base connector. The connect and disconnect of an xe2x80x9cactivexe2x80x9d operational portable computer system to and from an xe2x80x9cactivexe2x80x9d expansion base unit (sometimes referred to as xe2x80x9chot dockingxe2x80x9d) presents several difficulties. First, the risk of device latch up, which often leads to a peripheral device, processor or both, xe2x80x9cfreezing upxe2x80x9d and ceasing operation is present. Device latch up occurs when a device pulls excessive current through the expansion base connector due to sudden and unexpected signals and power levels. While latch up may destroy or damage a device, the use of protection circuitry in most modern day components can protect the device but still render it inoperable until the user cycles power by turning the system OFF and then ON.
Other known problems with interfacing an active portable to an active expansion base unit are signal glitching and cycle corruption. Timing differences between the signals appearing at the output of the expansion base connector and the input of the device interface contribute to such signal problems.
Moreover, the physical contact at the expansion base connector may cause signal breaks which are interpreted as false conditions by the system processor. The end result may be an incorrect command sent to the system controller, loss data segments, process interrupt sequences, loss of video or system memory, slow system performance or system freeze as well as other faulty conditions.
Accordingly, it is one object of the present invention to provide a method and device of interfacing active device components without effecting overall system performance or function. This is accomplished by generating a connect or disconnect interrupt signal which is intercepted by the system processor to cause system activity to be suspended during for a period of time while the connection is completed.
Another object of the present invention is to provide a method and device of interfacing operative devices that accounts for differences in device power states. A power state defines a device""s power-on/power-off status at the time of connection or disconnection. In this regard, the invention enables nonintrusive connect and disconnect in all possible power state configurations.
Yet another object of the present invention is to provide a device interface method and device that determines the status of a device connection. Dedicated signals on the expansion base connector are used to determine if a docking or undocking event is about to occur. A set of contacts on the expansion base unit generates an interrupt to the portable computer system processor when docking is occurring which suspends activity for a predetermined period of time enabling signal synchronization between the portable system processor and the expansion base unit. Device latch up is avoided by using make-first break-last type contacts at the expansion base unit interface ensuring that a complete connection is made for power prior to signal mating.
Still another object of the present invention is to provide a method of disconnecting operable devices that minimizes device freeze up during undocking of the portable computer system from the expansion base unit. A lever maintained on the expansion base platform actuates the undocking procedure and initiates an interrupt to the processor. All outstanding commands and system requests are terminated prior to the physical disconnect from the expansion base unit.
The expansion base unit is programmed to power-down peripherals maintaining them in a dormant state until subsequent docking. The portable computer Basis Input/Output System (xe2x80x9cBIOSxe2x80x9d) communicates with each active device via the Peripheral Component Interface (xe2x80x9cPCIxe2x80x9d) and reconfigures each device as part of the interface process in order to set each peripheral in its native power-up operational mode.
Disclosed is a method and device of connecting an active computing device to an active peripheral option comprising the steps of making a physical connection between the device and the option wherein the option is communicably linked to one or more peripheral devices. A system interrupt signal is generated to suspend all activity along the signal path between the device and the option.
For a more complete understanding of the present invention, including its features and advantages, reference is now made to the following detailed description, taken in conjunction with the accompanying drawings.